1. Field of the Invention
The present invention relates to an organic light emitting display device and a method for driving the same.
2. Discussion of the Related Art
Generally, an organic light emitting display device is a self light-emitting device that displays images by allowing an organic light emitting device to emit light through recombination of electrons and holes. This organic light emitting display device has received much attention as a next generation flat panel display device, owing to its advantages of fast response speed, low power consumption, and excellent viewing angle characteristic based on self-light emission.
The organic light emitting display device of the related art includes a plurality of pixels formed in pixel regions defined by the crossings between a plurality of scan control lines and a plurality of data lines. Each of the plurality of pixels includes an organic light emitting device and a driving transistor for controlling a current flowing in the organic light emitting device.
According to the organic light emitting display device of the related art, as such characteristic deviations as a threshold voltage Vth and mobility of the driving transistor are generated for each pixel due to a process deviation, the amount of current for driving the organic light emitting device is varied. For this reason, a luminance deviation is generated between the pixels. To solve this problem, the Korean laid-open patent No. 10-2013-0066449 having a counterpart of US 2013/0147694 A1 (hereinafter, collectively referred to as the “related art reference”) discloses the external compensation technology for compensating for a characteristic variation of a driving transistor included in each pixel through a data correction. In other words, according to the related art reference, the characteristic variation of the driving transistor is compensated for by externally sensing a characteristic variation of the driving transistor included in each pixel, generating a sensing data, calculating a compensation value corresponding to the sensing data, and then using the compensation value in determining the pixel data to be supplied to the corresponding pixel.
However, the external compensation technology disclosed in the related art reference has a problem in that a characteristic variation of the driving transistor cannot be compensated for if the compensation value based on the characteristic variation of the driving transistor is more than a set threshold compensation value. In other words, since there is a set limit in the compensation value for compensating for the characteristic variation of the driving transistor through data correction, as shown in graph (a) of FIG. 1, the characteristic variation of the driving transistor may be compensated for to the extent that the compensation value for each pixel is less than a threshold compensation value VLimit. However, as shown in graph (b) of FIG. 1, the compensation value for each pixel exceeding the threshold compensation value VLimit is limited by the threshold compensation value VLimit, whereby the characteristic variation of the driving transistor may not be adequately compensated for.
Accordingly, the organic light emitting display device disclosed in the related art reference has a problem in that the driving transistor is degraded when the organic light emitting display device is driven for a long period of time.